Pyramid

A pyramid (from Ancient Greek πυραμίς (puramís) 'pyramid', from the Egyptian pir-em-us, the vertical height of the structure.) is a structure whose visible surfaces are triangular in broad outline and converge toward the top, making the appearance roughly a pyramid in the geometric sense. The base of a pyramid can be of any polygon shape, such as triangular or quadrilateral, and its surface-lines either filled or stepped.

A pyramid has the majority of its mass closer to the ground with less mass towards the pyramidion at the apex. This is due to the gradual decrease in the cross-sectional area along the vertical axis with increasing elevation. This offers a weight distribution that allowed early civilizations to create monumental structures.

Ancient civilizations in many parts of the world pioneered the building of pyramids. The largest pyramid by volume is the Mesoamerican Great Pyramid of Cholula, in the Mexican state of Puebla. For millennia, the largest structures on Earth were pyramids—first the Red Pyramid in the Dashur Necropolis and then the Great Pyramid of Khufu, both in Egypt—the latter is the only extant example of the Seven Wonders of the Ancient World.

The Mesopotamians built the earliest pyramidal structures, called ziggurats. In ancient times, these were brightly painted in gold/bronze. They were constructed of sun-dried mud-brick, and little remains of them. Ziggurats were built by the Sumerians, Babylonians, Elamites, Akkadians, and Assyrians. Each ziggurat was part of a temple complex that included other buildings. The ziggurat's precursors were raised platforms that date from the Ubaid period of the fourth millennium BC.

The earliest ziggurats began near the end of the Early Dynastic Period. The original pyramidal structure, the anu ziggurat, dates to around 4000 BC. The White Temple was built on top of it circa 3500 BC. Built in receding tiers upon a rectangular, oval, or square platform, the ziggurat was a pyramidal structure with a flat top. Sun-baked bricks made up the core of the ziggurat with facings of fired bricks on the outside. The facings were often glazed in different colors and may have had astrological significance. Kings sometimes had their names engraved on them. The number of tiers ranged from two to seven. It is assumed that they had shrines at the top, but no archaeological evidence supports this and the only textual evidence is from Herodotus. Access to the shrine would have been by a series of ramps on one side of the ziggurat or by a spiral ramp from base to summit.

The most famous African pyramids are in Egypt—huge structures built of bricks or stones, primarily limestone, some of which are among the world's largest constructions. They are shaped in reference to the sun's rays. Most had a smoothed white limestone surface. Many of the facing stones have fallen or were removed and used for construction in Cairo. The capstone was usually made of limestone, granite or basalt and some were plated with electrum.

Ancient Egyptians built pyramids from 2700 BC until around 1700 BC. The first pyramid was erected during the Third Dynasty by the Pharaoh Djoser and his architect Imhotep. This step pyramid consisted of six stacked mastabas. Early kings such as Snefru built pyramids, with subsequent kings adding to the number until the end of the Middle Kingdom. The age of the pyramids reached its zenith at Giza in 2575–2150 BC. The last king to build royal pyramids was Ahmose, with later kings hiding their tombs in the hills, such as those in the Valley of the Kings in Luxor's West Bank. In Medinat Habu and Deir el-Medina, smaller pyramids were built by individuals. Smaller pyramids with steeper sides were built by the Nubians who ruled Egypt in the Late Period.

The Great Pyramid of Giza is the largest in Egypt and one of the largest in the world. At 146.6 metres (481 ft) it was the tallest structure in the world until the Lincoln Cathedral was finished in 1311 AD. Its base covers an area of around 53,000 square metres (570,000 sq ft). The Great Pyramid is the only extant one of the Seven Wonders of the Ancient World.